A critical review of gastric retentive controlled drug delivery.

The promise of gastric retentive drug delivery systems has propagated numerous investigations and the formation of a number of companies. Three technologies have involved a substantial number of human clinical trials: mucoadhesion, density modification, and expansion. Standard, nondisintegrating controlled-release tablets can display significant gastric retention times, with that retention time being proportional to the calorie intake. When these data for standard tablets are factored in, gastric retention technologies do not appear to offer significant additional retention times. Although the goal remains valuable, the promise of gastric retentive drug delivery systems remains unfulfilled at this time.